Police and prosecutors in Sacramento, Calif., are investigating the shooting death of an unarmed black man on Sunday night. Stephen Clark was shot by two police officers who were searching neighborhood backyards for a reported vandal. When they saw Clark, they thought they saw a gun. NPR's Martin Kaste tells us more. And a warning - this piece contains sounds of gunshots from the police bodycam video.

MARTIN KASTE, BYLINE: It started with a 911 call about a guy breaking car windows along a residential street. Police respond. And this is the newly released body camera video. They ask a resident if they can search the backyard.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED OFFICER #1: Can we check your backyard real quick? Supposedly, somebody just broke some windows over here and then ran through your yard.

UNIDENTIFIED WOMAN: Oh?

UNIDENTIFIED OFFICER #1: Yeah.

KASTE: But as the minutes ticked by, what starts out as a mundane vandalism call turns into a tense search. Dogs are barking. The sheriff's helicopter's hovering. And the two officers whisper to each other as they search with their flashlights, guns drawn.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED OFFICER #1: Can we get in here?

UNIDENTIFIED OFFICER #2: It's locked.

KASTE: Lou Hayes is a police officer and police trainer in the Chicago area. He says, at this point, you need to put yourself in the shoes of these two cops.

LOU HAYES: It's kind of like going back and playing hide-and-go-seek as a kid, where you start getting that little anxiety once you start getting close to where you think someone's hiding. So there's definitely a heightened sense of arousal, of adrenaline.

KASTE: And then the cops come around the corner of a house, and they see someone.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED OFFICER #1: Show me your hands. Show me your hands. He has a gun.

(SOUNDBITE OF GUNSHOTS)

KASTE: It's dark, and a shadow goes down. The cops hold their position for a bit calling out to the man. And finally when reinforcements come, they check his body. He wasn't holding a gun. It was a phone. And as it turned out, he was shot and killed in his own grandparent's yard.

BARRY ACCIUS: Why did you have to use excessive force in this situation?

KASTE: Barry Accius is a prominent black activist in the Sacramento area.

ACCIUS: What happened to all the other things that we have been told in a community that they would try to do before apprehending an alleged suspect? And what were those stages? Like, what happened in that moment where they felt that excessive force was needed?

KASTE: That's the question Sacramento authorities are now looking into, with the involvement of local prosecutors. Lou Hayes says, at first glance, this video shows officers who may have been urged on by the adrenaline of the moment but kept their heads - bad as the aftermath may look.

HAYES: The cellphone is an after-the-fact determination. We have to add everything up together.

KASTE: But the police response doesn't add up for many people in Sacramento. The NAACP is meeting with the police chief. And as the investigation progresses, protests are planned. Martin Kaste, NPR News.